> Today I saw 3 drives in the service mode. I manually changed the mode
back to "enabled"
> But it automatically went back into "service" mode.
> What could be the prob ?

You're probably suffering from persisten binding problems, a known
Windows/Networker issue..... 

Look at the content of the drives, is tape A in \\.\Tape0?
Now check the physical drive for its contents... Is tape A really there?
Or is tape A in \\.\Tape1? And B in \\.\Tape0?

If so, or something much like it :-) you should check:

- latest drivers from your Tape/Library/HBA/SCSI controller (OEM)
Manufacturer
- latest OS updates from Microsoft (as you're running Windows)
- check esg83905
(https://solutions.emc.com/nsepn/webapps/stqv768481dmts46655278/emcsolut
ionview.asp?id=esg83905)
- and the Microsoft Knowledgebase article (mind the version, there are
actually 2 articles for W2K and W2K3) 873337
(http://support.microsoft.com/kb/873337/)

Good luck,
Alex

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